1. Field of the Invention
This invention relates to devices used for illumination of target objects by electromagnetic radiation. In particular, this invention relates to illumination devices having multiple beams, each of which can have selected wavelength, bandwidth, pulse duration, pulse frequency and intensity.
2. Description of Related Art
Physical treatment of disorders associated with the peripheral nervous system is becoming increasingly important in the management of disease. Acupuncture, acupressure and related healing arts typically involve the mechanical stimulation of peripheral sensory and motor nerves. In acupuncture, needles are typically inserted through the skin to reach the desired locations. Acupressure involves the application of localized surface pressure above the desired site and the transmission of that pressure to the nerves under the skin.
Stimulation of peripheral nerves can be accomplished using heat or infrared radiation. Infrared radiation can be produced using lasers or sources of incoherent electromagnetic radiation.
There is a need in numerous technologies for providing two or more selectable wavelengths of radiation. Examples include electromagnetic radiation therapy, fluorescence microscopy, contrast enhancement for photography or machine vision, and simulation of radiation combination effect from sources of radiation having narrow spectral ranges, such as light emitting diodes (“LEDs”), and characterization of the quality of optical systems.
There is also a need in the art for inexpensive devices that can produce electromagnetic radiation of discrete wavelengths and deliver beams of those discrete wavelengths separately from one another.
A variable bandpass tunable filter system is available commercially from Ocean Optics, Inc. that consists of two filters, each coated with a linearly variable multilayer interference coating, providing a “wedge” filter. To select a bandwidth, two filters are placed overlapping each other, in series with the source of radiation, so that a beam of radiation passes through both filters. To increase the bandwidth of output radiation, the two filters are offset relative to each other. Although this system can provide output variable bandwidth, because the output radiation must pass through both filters, desired wavelengths the output beam will be reduced in intensity.
Therefore, there is need in the art for inexpensive illuminators that can provide output beams of electromagnetic radiation having controllable wavelength, bandwidth and intensity.